Binding Souls
by Prinxessvin264
Summary: The mark wouldn't start shifting until you find your soulmate. The moment he set eyes on him, his mark began moving. But he never saw him again. Ereri-Soulmate AU.
1. one

**-Disclaimer-**

 **I don't own Shingeki no Kyojin.**

 **-Summary-**

 **The mark wouldn't start shifting until you find your soulmate. The moment he set eyes on him, his mark began moving. But he never saw him again.**

 **-Prologue-**

Ever since Eren was ten, his mark started changing. He knew who his soulmate was, a bit fuzzy in his memory but still, a split second glace at him was all it really took.

Really, it didn't matter that it was a he, or even that the guy was older than him. All that mattered is that he was _his_.

He remembered how his hand burnt without pain, how his mark, attatched from the back of his hand, moves from one shape to another, a color to another. He never got tired of it.

He knew when his partner was angry, sad, lonely, but there were also times when he was happy, but it was just a faded yellow coin, which meant that the man was surpressing his feelings. And whenever it would shift to a bird in grey color, he would wish his partner knew of him that he wouldn't be lonely. He wished they were together.

He knew his partner hadn't know of him yet, the only proof he saw was the still mark at his hand that day. The problem is, he had his back towards Eren.

The rule of the marks were that even though one saw the other, only he or she who saw will know of their soulmate. It doesn't work both ways. There were some who died without knowing of their soulmate, even though they'd cross paths once or twice.

Some died with only seeing there soulmates once, but fate was too cruel playing with them then.

He wondered if he'll see him again.

But once the soul mate was gone, taken by death, their marks would fade to nothing. And the ones left by the partner would forever be destined to be alone.

The mark can determine who you'd fall for, and who'd fall for you, it's assured. But it can't lengthen the thread of one's life.

Not to mention, they live in a world ruled by titans.

That day, he made it his goal to join the ones with the Wings of Freedom. His desire to join only got stronger when he heard people talking about them like trash. He understood the world's cruel ways by then.

He remembered when his parents first noticed his mark, they did asked a lot of questions, who was the lucky girl, when did you two meet, why wasn't his blue or in the form of wings anymore, did it hurt when it was shape shifting, how did he get it at such a young age. He'd just laugh at them.

And when he told them about him, he bursted in another fit of laughter on the looks they had on their faces. When he'd composed himself, he heard them say they wouldn't mind, as long as he's happy. And he was glad it all still turned out well.

Then Mikasa came. At first, Eren had misunderstood her feelings for him. He took the signs wrong.

Who wouldn't, Mikasa would blush when it was Eren, she's always protecting Eren, she's all over Eren. When he confronted her about it, she laughed. She laughed at him for, apparently, asking a ridiculous question.

Mikasa said she had already found her soulmate too, and they were keeping in touch at such long distance. How would he even know that? She hadn't told him his name though. It was all in due time, she said.

For the next few months, he was always found at the gates whenever there were soldiers from the Survey Corps who would return from battle, hoping he would see him again. But he never got the chance to.

That day had come.

- _Riren_ -

Levi isn't one to beleive in soulmates. When he was a kid, he had always wondered what his partner looked like. It was when his mother was still alive, when he still lived in a dream.

He'd laugh whenever he recalled how ambitious, pretentious the kid was when his head was still in the clouds.

Now he couldn't quite understand why he'd been so foolish.

 _Love is for the weak. I don't need a soulmate, that never even existed_.

He'd lost them, the ones he cared for deeply. Why was the world so cruel to him anyway? Karma would've been laughing at him for his stupidity.

Although his friends all had soulmates, Furlan to Isabel, Erwin to Petra, Hanji to... well, maybe she's destined to her titans. The only indication she was ever destined to someone was her frequently changing mark.

He didn't know why he still bothered to look. He had a habit to unconsciously glance at his forehand every time he was in deep thought, only resulting to him reminding himself of a cruel fate.

His mate might be living right now, with his mark still there. But fate might not give them a chance to meet. In the end, it all depends on fate, right?

"Wrong." Hanji would tell him. "Try harder, then you might find your answer."

Yeah, right. He'd rather save humanity from getting eaten than searching the _imaginary_ mate of his for the rest of his life.

So with a tired sigh, he brushed his hand to his hair and continued his work. Tomorrow will just be another long and boring day.

Atleast they'd spend it in an expedition beyond the walls.

But things took at turn for the worse that same day.

- _Ereri_ -

 **I couldnt think of a better title, so I settled for a common one :3**

 **Next chapter?**

 **Please review, follow, favourite. Thanks!**


	2. two

The next time Eren saw him, was in a cell. Those steely grey eyes, fixed solely on him. Only, those eyes held nothing in them.

Eren's eyes instinctively flickered to the man's forehand, only for a split second. And that was enough for him to note the glove the man wore. It looked badass, but it made Eren whine silently.

But he did felt the burning of his own, that it was changing once more. It was there, and he understood.

Pokerfaced captain held no emotion on his features, but he is only human too.

Eren's sign shifted to a grey bird in the center of a inch wide, pitch black dot, only means that Levi was _trying_ to figure him out. _Trying_ to find the gate- an entrance _and_ an exit -in a dark cave. He was subconsciously putting the puzzle pieces together, and the missing piece was _right in front_ of him, but transparent to _him_.

If only he would look at his own mark.

What's worse came; Levi acted as if Eren was just a pain in the ass. Like, just somebody. Just _anyone._

He did beat him shitless on the trial. But Eren knew it was just to save him. He trusted him enough for that.

But the next few days were hell for the shifter.

Levi calls him brat often, he didn't mind. Eren actually thought of it as his very own pet name. Levi makes him clean for hours and hours non-stop, that clean freak punishes him whenever he didn't do it right. The midget even made him run 'til he drops dead once when he accidentally spilled tea on the captain's quarters. It almost looked like his captain had a hidden resentment towards the titan, but his mark proved them wrong. To him at least.

He often wondered why his captain had acted indifferently around him. They had met, even bounded to be together.

Does Levi even care about his partner's existence? He _is_ cold hearted and cruel, so they say, but Eren can see how he acts different to those whom he cares about, even just a little.

Eren could tell the difference on how he acts towards him and towards his squad. It wasn't the same. By a long shot.

He took back what was said before. The cold hearted captain being _his_ didn't matter. Not this time. This was _way_ worse that not getting to meet your soul mate.

 _Damn all these thinking is making my head ache._ Eren thought as he got back to cleaning. Any second now, the raven would check up on him, maybe make him redo once or twice, before letting proceed to the next room.

 _We should be training to kill titans instead!_ he huffed angrily, furiously sweeping the wooden floor. _Honestly, how can heichou tell the difference? It looks so clean already!_

A few moments later, he heard light footstep coming his way. Quickly, he looked around for any sign of dust or dirt, every corner of the room, every inch his captain can see. He thought of skipping the higher shelves, ones that even tiptoeing, Levi couldn't reach. Eren chuckled. How can someone that small, fit a great amount of strength and power within themselves? He wouldn't know, more so ask.

The door opened, lightly creaking a creepy sound, and in came a midget.

Eren immediately stood up in a straight posture, saluting Levi.

Levi did check up on his work, but let him proceed onto the next room. When Eren sighed a few breaths of relief, the raven glanced over his shoulder, and only then did Eren notice a smile on his face. Only for a split second.

Eren stole a glance at his forehand; it had become a habit for whenever the captain would falter on his movements and subconsciously fit the puzzle pieces over and over again, he did just that. It was easier to know what to do and when to do it.

But it had it's down sides as well.

Of course, not even the mark was perfect; nothing is.

There were times when it would make the wrong signs, like glitches. Only those who had it for years would've noticed- might have. It was based on experience.

Those times were when Eren almost, _almost_ embarrassed himself in front of everyone in the Scouting legion if it wasn't for his- surprisingly -composed self when it came to these matters.

At least no one would have noticed. Or, maybe at least most of them wouldn't.

There was only one person who knew about his mate. Moblit, from Hanji's squad, had been the only person to whom he could share his stories to. Well, him and Hanji, but he doubted he could call her human. Hanji was the first to know, mostly because of the titan experiments.

* * *

It was a normal day at the Survey Corps, and Eren was with the Megane for experiments. Levi was out with Erwin and Mike.

Eren was being tested and tampered with, when Hanji caught a flash of movement in her peripheral vision. She glanced at the source, gasping and squealing in what Eren could only guess as excitement.

"Oh my gosh! You have met your mate?" When Eren nodded, she gasped once more, before taking his hand and examining it. "Oh my, I wonder how she will affect your shifting... maybe we could try! Bring her here Eren, and we'll test how your body will react to the mark's will."

"I have a bad feeling about this." Moblit said from the sidelines. "What are you planning on doing with 'her'?"

"Oh, you know. See how he'll react when she's in pain or something disquiet, how the mark and his titan self, _together_ , would respond to it." Hanji turned to Eren, who had paled a bit on what the scientist had said. "Has it ever happened before? The shifting being affected by the mark, I mean."

Eren shook his head. "Not that I know of, no..." he paused, "I don't think he's ever been in physical pain before... emotionally, quite a lot, but physically- it's quite rare."

There was a long pause, before Hanji raised an eyebrow, blinking continuously. " _He_?" Eren realized his mistake and blushed, looking off to the walls on the other side of the room. He heard Hanji say something in a hushed voice, but in a tone full of mischief. "Now I really have to know of this, detailed."

He could see Moblit roll his eyes at his partner. He could sense Hanji trying to stifle her laughter. And he could really feel the annoyance radiating off from his mark. At least he wasn't alone.

They finished up quickly, as Hanji's rather excited on hearing his story.

"...yeah, I first saw him when I was nine." The titan shifter sighed mentally. Whether he liked or not, Hanji would not let him go easily, since she was a curious cat and wouldn't stop prying until she's satisfied. This is the easiest way out. "I think he was a new recruit at the Survey Corps? Anyway, that was the last time, and I thought I would never see him again, so I decided to join here, to change our fate. I knew I was gambling, a fifty-fifty chance at losing him beyond the walls was high enough to make one lose their will. But I'm pretty stubborn, so I'd still play with fire unafraid of getting burnt. Though I did hate the titans enough for me to forget him for a bit, but the goal was subconsciously stuck with me. I guess from the moment I met him, anything I do, I'd still be fated to end up in this place."

"You're always saying 'him'. Care to name them?" Hanji had this exasperated look on her face, one that Eren found quite funny.

"...If you promise not to tell them." When he had gotten his nod of approval, he hesitated. "...C-corp-poral.. L-Levi..." he told her in a really hushed tone, they wouldn't even hear if the room wasn't drowned in silence.

Hanji sat up abruptly after it sank in, startling Eren and Moblit in the process. Her soulmate was still in a state of shock, but had recovered by the medicine named as her screams and squeals of excitement. "I knew it! I knew Levi had some one out there! I knew he had a real mark, not a tattoo drawn just cause he didn't have one!" She kept repeating. The last part confused Eren, but he didn't ask.

Hanji halted on her steps, turning to the boys with wide eyes and a grin so wide, Eren was afraid it would tear her face apart. "We should tell Levi!"

"No!" Eren reacted quickly, before he noticed what he hade done. "I'm sorry, Hanji-san."

"It's alright, Eren." she gave him a reassuring smile. "But why would you want to keep it from him?"

"It is for the better. I don't think he would want a soul mate anyway, much less me. Besides, it will hurt more to get rejected rather than stay in the sidelines- where I could stick close to him most, as close as he would let me anyway."

Hanji felt for the boy. She knew it was true, Levi though of his soul mate crap, didn't give a shit about the topic, and never once had dared to search for the one, even with her and his other friends' insistence. Heck, he'd let them get eaten by titans for all he cared.

Levi had decided to forget about the pain. He had endured enough, that he'd just forgotten- pushed every thought of it in the deepest, darkest part of his mind. But forgetting it had its price; forgetting his soul mate along with it.

He ought to forget that he had someone to care for, someone to protect, to love.

He ought to forget he still had _someone_. But who would've though that that _someone_ was right under his nose.

Indeed, fate was cruel. It seemed it has decided to play its little games on them, of all people.

Really, being Humanity's Strongest and Humanity's Last hope had their prices to pay.

Nothing is free in this world after all.

"Go get some rest, Eren." Hanji didn't know what to say or do, so she ought to send him away for a while. Those pained words and remorseful memories would take a toll on both physical and mental health, so he would really need to take his time.

All Hanji could think of at the moment was apologizing to he boy for even asking about it, and feeling guilty and sad for Eren, but she doubt that was what the boy wanted. "We're done now-" _I'm sorry._ "you're free to go."

Eren nodded, walking out of the room and leaving the couple in silence. Tension was felt in every corner of the room. Moblit may not see it in his mate himself, but the feel of his mark was enough to render him speechless. It was so uncharacteristic of Hanji to dart her eyes everywhere every second that passes, for her to open and close her mouth like a fish. Minutes felt like hours; no one cared for how long it had been.

When Hanji finally spoke up, the tension only arose. "Why does it have to be them of all people? I know being Humanity's last chance at freedom redemption had its prices, but this- is just _too much_. When will it be _enough_?"

Moblit grabbed her hand and pulled her to his chest when she began to spill tears she was holding back. She continued nevertheless, her voice broken. "They have suffered enough, lost too much, been through a lot. But why isn't it still enough?" Hanji laughed bitterly as Levi's words struck her painfully.

 _"In the end, it all depends on fate right?"_

* * *

Eren flopped down his bed, not even caring about cleaning himself. He knew the captain will be mad and scold him, but he couldn't bring himself to care at the moment. He glanced at his forehand.

His thoughts drifted to Levi. _They_ , would never work out. Anyway you look at it, it's just- no. Not in this situation anyway.

Levi had seen his mark a couple of times, but didn't bring it to topic even once.

Eren knew the captain doesn't care about anything in that field. Only titans and his job. And his friends. But not Eren.

So what's the point of hoping and getting all gloomy about it? It's not like it will ever happen anyway.

It will also just distract them from freedom and vengeance, so they're better off without them.

But can he really keep his love and adoration for the midget for long? After all, no secret lasts forever.

 _Why was fate so cruel?_

His gut wags screaming at him to not back down, but the other part of his gut was also screaming ' _what should I not back down from_ '?

For the rest of the week, Eren Jeagar had always fallen asleep on these trains of thoughts. It was full of questions and self debates, but he only came to one conclusion.

He would play this game, and he wouldn't be backing down anytime soon. Even though he had little to no clue what is it he was playing exactly.

There was a tug in his mind. He just felt the need to. And if so, then so be it.

* * *

 **Sorry for the long wait! I had trouble putting things together since I have made a few adjustments, so it took me a while.**

 **This fan fiction was unplanned too, I have been planning a few things though. Please don't be surprised when stuff pops out of nowhere. XD -Partly kidding-**

 **We'll just see how things will progress after a few chapters. It may or may not end by then.** (^^ゞ

 **Please review, follow, favourite. Thanks!**


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